SEATTLE - George Springer felt he could play Thursday in the opener of a four-game series against the Mariners, but the Astros held their prized young right fielder out of the 3-1 loss because of a right hip flexor strain suffered Wednesday in Anaheim.

Springer was hurt in the ninth inning of the Astros' 2-1 loss when he was picked off first base by Angels pitcher Jered Weaver He was limping and in visible pain at the time, but shortly after the game, he said the pain had subsided.

Springer said he would cautiously take outfield work Thursday but would not hit on the field during batting practice at Safeco Field. He said he also dealt with a hip flexor strain when he was in Class A ball and reiterated that he knows his body well.

"It's not something that you want to risk any further damage," manager Bo Porter said. "He wants to play, but that's the player - they always want to play."

Porter didn't rule out the possibility of Springer's returning Friday.

Springer was confident he would not need a trip to the disabled list and understood that taking a day off now could prevent more time off going forward.

"I came in, I said I can play, that's how I feel," Springer said. "If I'm physically able to play - I woke up today, I'm happy, I'm breathing, so I can play. … I'm going to be smart about it, see how I feel, not try to aggravate anything else."

Springer has a .426 on-base percentage in the 10 games he has batted in the two-hole, a spot he took over on a full-time basis a little more than a week ago. He's hitting .240 with a .326 OBP and four home runs overall.

"I like playing every day. I'm an everyday kind of guy," Springer said. "When you're not playing, it's tough."

Luhnow scouts top prospects

General manager Jeff Luhnow said he has seen all the prospects the Astros might take with the first overall pick in the June 5 amateur draft, including high school lefthander Brady Aiken, whom Luhnow watched pitch Monday.

Luhnow was in Southern California with the Astros for the three-game series they played against the Angels at the start of the week.

Aiken, a 6-4, 210-pound lefthander attending Cathedral Catholic High School in San Diego, has an advanced feel for pitching with a projectable body, according to Baseball America. He has hit 97 mph but sits in the low 90s this spring, with a curveball leading his secondary stuff. He has a low-effort delivery and is committed to UCLA.

Shepherd High flamethrower Tyler Kolek and lefthander Carlos Rodon of North Carolina State also are considered to be possibilities for the Astros.

Luhnow was with the Astros in Seattle on Thursday before heading to Japan on Friday for a five-day trip. Astros pro scouting director Kevin Goldstein also is going to Japan.

Peacock finds his zone in May

Brad Peacock, Friday's Astros starter opposite Mariners ace Felix Hernandez, has gone at least six innings in all four of his starts this month. His 4.62 ERA for May doesn't reflect dominance, but he's striking out more batters this month - 9.2 per nine innings - after starting the year in the Astros' bullpen.

"One of the biggest things is he started to pitch to the top of the strike zone," manager Bo Porter said. "You look at last year, at his heat maps and when he started to just get in trouble, it was like everything was at the bottom quadrant of the zone, and he never really changed the hitter's eyesight."

According to BrooksBaseball.net, almost all of the damage off Peacock this year has come on pitches middle-in, which isn't atypical. Using a slider he added in 2013, Peacock might have opened more of the outside of the plate for himself.

"I think the slider plays into that - whenever you start to elevate the baseball and the hitter not only has to worry about hard stuff at the top of the zone. Obviously, he had commanded the bottom of the zone with great effectiveness," Porter said. "But now you're talking about opening up the zone."

Appel to go into tandem rotation

When top pitching prospect Mark Appel leaves extended spring training after one more outing Tuesday, he won't be treated differently than any other pitcher in the Astros' modified tandem rotation in the minors, general manager Jeff Luhnow said. Class A Lancaster, Appel's original team, is where he's slated to go.

In the modified tandem, pitchers fluctuate between days when they make a traditional start that is theirs alone and days when they start with their tandem partner in a piggyback outing.

"He will be pitching in this same system, so there will be times when he has his own start and is able to go deeper into games, but there will be times when he's going with (a tandem partner)," Luhnow said. "It fluctuates. So you're either on a five-man rotation cycle or a six-man rotation cycle."

Luhnow didn't have a timetable for high-ceiling pitching prospect Vincent Velasquez to return from a groin strain. A teammate of Appel's at Lancaster to start the season, Velasquez will be taken slowly because groin injuries are particularly tricky.

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